For people whose roots are embedded in the mainframe IBM world,
client-server is essentially distributed or remote presentation. This style
maps a workstation Graphical User Interface (GUI) front end onto an
existing application's text-based screen. This is also called Remote,
Mapping, Front-ending or HLLAPI (High-Level Language Application
Programming Interface). The mode of operation is typically intelligent
workstations intercepting and interrogating text-screen (e.g. 3270) data
streams sent from a host for display in a windowed environment.This is
"frontware" solution, where a GUI front end is added to an IBM/MVS
3270/5250 application and is placed on a workstation. However, most
processing remains on the host or server, with the exception of user
interface translation logic and possibly validation logic. For example,
data from an application program is sent to a 3270 screen program on the
mainframe to be displayed. The merged data is sent to the workstation as
a 3270 data stream.The workstation interprets the data and converts it to
graphical form in a window. (Typically every mainframe screen used by
the application has a corresponding window on the workstation and vice
versa). When the user enters the data in a GUI window, it is transformed
by the frontware application into a corresponding 3270 data format and is
sent to the host computer.

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